Rome
Samba Member
Joined: June 02, 2004
Photos: 4412
Location: Pearl River, NY
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| Hand-lapping board for small parts |
Posted: Wed May 26, 2021 7:18 pm Views: 15
Rating: Not rated
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| Over 30 years ago I made a simple tool to hand-lap surfaces flat; something you can make in less than an hour for probably under $10. I bought 2 clipboards for 8 1/2 x 11" paper. Back then the cheapest ones were the hardboard ones; nowadays you can also buy plastic ones. Drilled the rivets that held the clip off one of the boards, held the removed clip in place on the first board at the other end from that one's clip, marked the 2 attachment holes, and drilled them in the board. Attached the clip with some 1/4" grip length rivets with backing washers. I went to a HW store and bought a single glass mirror tile that was about 10" square. Slipped that under the two clips, with a sheet of 220 wet sandpaper on top that's also held in place by the two clips. The clips prevent the sandpaper from sliding. Use water or WD-40 as lubricant. The reduced friction usually enables the clipboard to stay in place on the workbench; if it moves I'll hold it with my other hand or use 2 woodworking spring clips to hold the board to the workbench edge. Use 30-40 back & forth sanding movements in one direction, then lift the part and rotate quarter turn and do 30-40 more. Lift up the part, wipe it off with paper towel, and closely observe the sanded area. When you see that the sanding marks reach the various attachment holes and extend around them to the part's edge (arrows), then you know the surface is fully flat. I use this method on many parts, such as cylinder top edges, fuel pump housing surfaces, oil pump housings. |
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